Ladder construction



Jan. 16, 1962 D. J. MUNSON LADDER CONSTRUCTION Filed Sept. 28, 1959 m mm w.

230M440 I Mam/501v @400 United States Patent 3,016,976 LADDERCONSTRUCTION Donald J. Munson, Minneapolis, Minn., assignor to The J. R.Clark Company, Spring Park, Minn., a corporation of Minnesota FiledSept. 28, 1959, Ser. No. 842,702 1 Claim. (Cl. 182-194) This inventionrelates generally to stepladders and more particularly concerns stepconstruction and means for mounting the steps between the ladder siderails.

The primary object of the invention is to provide a novel and improvedstepladder construction which provides for secure mounting of metalcross members such as steps between wooden side rails without the use ofnails, rivets, tie rods or other independent fastening devices and whichappreciably strengthens the side rails in the area of mounting comparedwith conventional construction wherein the rails are weakened bygrooving procedures.

Another object of the invention is to provide a new and improvedstepladder construction which readily lends itself to automation in themanufacture and assembly thereof.

Still another object is to provide a ladder construction wherein thedepth of step contact with the side rail and the rigid connectiontherebetween render the ladder more resistant to side sway.

With these and other objects in mind the invention broadly comprises aside rail and step assembly in a ladder wherein a sheet metal step ismounted between wooden side rails by providing the step with integrallyformed tubular portions extending longitudinally of and endwise beyondthe step, the tubular portions extending outwardly through apertures inthe side rails and washer plates therebeyond and having their terminalend portions flattened against the washer plates to hold the railsfirmly against the ends of the steps.

The above mentioned and additional objects of the invention will bebrought to light during the course of the following specification,reference being made to the accompanying drawing, in which FIG. 1 is aperspective view of the upper portion of a stepladder embodying theimproved construction of this invention.

FIG. 2 is a front elevation of one of the steps of the ladder partiallybroken away to show the connection between the step and one of the siderails.

FIG. 3 is a perspective view of one of the ladder steps before assemblywith the other ladder components.

FIG. 4 is a cross section through one of the ladder steps taken on line4-4 of FIG. 1.

Referring now more particularly to the drawing reference numerals willbe used to denote like parts or structural features in the differentviews. The ladder is designated generally at and is the collapsible typewith side rails 11 and brace legs 12 respectively having their upperends pivoted as at 14 and 15 to a stop platform 16. A pail shelf 17 ismounted on the ladder by collapsible linkage 18 pivoted to the rails at19 and the brace legs at 20 so that the shelf might be foldedsubstantially into the common plane of legs 12 when the legs 12 andrails 11 are closed together for storage of the ladder. The brace legs12 may be interconnected by a transverse brace member 21.

The side rails 11 are interconnected by a series of vertically spacedsteps 22. In this construction the side rails and brace legs are made ofwood while platform 16, pail shelf 17, brace 21 and steps 22 are ofmetal.

Each step 22 is formed of a single sheet of metal and will now bedescribed in detail, reference being particularly made to FIG. 3. Thesheet is formed in an elonice gated inverted channel shape with a broadcentral tread portion 24 being provided with longitudinally extendingstrengthening ribs 25, formed in the sheet itself. The front wall 26 ofthe step depends downwardly in substantial right angular relation to thetread 24 with the lower edge portion thereof curled inwardly in anannular direction to form an integral tube or bead 28 extending alongthe bottom of wall 26. The tube portion 28 of the step is longer thanthe channel or body of the step and projects beyond the ends of the stepportions 24 and 26 as at 29.

The rear wall 27 of the step angles somewhat inwardly toward wall 26 inits downward extension and is provided with an integral tube 30extending along its bottom edge. This tube is similar to tube 28extending beyond the ends of the step proper as at 31. Each of theextensions 29 and 31 is somewhat longer than the transverse thickness ofrail 11.

The steps are mounted in position between the side rails by insertingthe tube extensions 29 and 31 through pre-drilled apertures 32 in therails, the apertures being so located as to receive said extensions withthe tread 24 disposed horizontally as the ladder is in erect condition.Washer plates 34 having apertures spaced to receive the extensions areplaced over the extensions and against the outside surface of rail 11.The ends of the extensions are then flattened or clinched against theplate 34 as at 35 to tightly secure the step endwise against the siderail with the end edge of tread 24 bearing firmly against the rail.

The mounting is accordingly readily eifected without the use of nails,bolts, rivets or tie rods. Moreover, the assembly affords an extremelyrigid connection between the step and rail without providing the siderail with step receiving gains which weaken the rail. The possibility ofside sway in the ladder is greatly minimized by the depth of contactbetween the ends of the step walls 26 and 27 and the rails 11.

It is also significant that the step is so formed that the railapertures for receiving tubes 28 and 30 are longitudinally offset toprohibit undue weakening of the rail at any one point.

Cross brace 21 utilizes a similar construction with tubes 37 beingformed along the upper and lower edges thereof projecting through thelegs 12 and washer plates 38 and being flattened thereagainst as at 39to prohibit removal.

The construction described economically and effectively carries out theaforementioned objectives. It is understood that suitable modificationsmay be made in the structure as disclosed, provided such modificationscome within the spirit and scope of the appended claim. Having nowtherefore fully illustrated and described my invention, what I claim tobe new and desire to protect by Letters Patent is:

A step ladder comprising wooden spaced apart side rails and sheet metalstep members, said step members extending between said side rails invertically spaced apart position with the end edges thereof engaging oneagainst each side rail, said sheet metal step members each being in theform of an inverted elongated channel in the provision of a centraltread portion and having depending front and rear walls dependingdownwardly at substantially right angles from opposite sides of saidcentral tread portion of the step, longitudinal elongated strengtheningribs formed in said step tread portion, said depending front and rearwall of each step having the lower edge curled inwardly in an annulardirection on the lower edge of each respective wall, said lower curlededge of each wall extending beyond the length of said respective stepmembers at each end in the provision of two spaced apart tubularextensions at each end of each respective step, said spaced apart woodenside rails each having oppositely positioned vertically spaced aperturestherein, whereby the said tubular extensions of said respectivevertically spaced steps project through said apertures, and a metalplate for each step likewise having oppositely positioned spacedapertures therein alignable with each of the respective spaced aperturesof said Wooden side rails, to thereby receive the said respectivetubular extensions of an adjacently positioned step memher, said plateserving as an anvil and said free ends of said tubular extensions beingdeformable into a flattened head portion against the exterior surface ofsaid metal anvil plate to tightly secure the respective adjacent stependwise at each end between the said side rails.

References Cited in the file of this patent UNITED STATES PATENTS901,755 Tiepolt Oct. 20, 1908 1,445,513 Wilford Feb. 13, 1923 1,683,422Stevenson Sept. 4, 1928 2,090,331 Kutscheid Aug. 17, 1937 2,478,592Nyberg Aug. 9, 1949 2,844,292 Rich July 22, 1958 2,951,550 Rich Sept. 6,1960

